Max safe voltage ?

[stanames]

This question is not as simple as it might seem. To answer it you must first understand what NMRA S-9 requires. This basic electrical standard is what the industry has been using for years. It does need to be updated for Z and Large Scale but the fundamentals remain the same.

NMRA S-9 requires that at full load you must be able to deliver 12 volts to the motor.

Most DC power packs do not have voltage regulation. To deliver 12 volts under full load requires an unloaded voltage of between 16-18 volts. The reason is that as you increase the load the voltage will drop.

For DCC you need to add 2 volts to the track voltage because of the decoder and because of the transitions in the DCC signal (actually 1.5-1.8 is enough but the standards call for 2 volts.)

Most high end systems and many mid range systems have some form of voltage regulation but most still have some voltage sag under load. In addition with both DC and DCC there will be voltage losses in the wiring and track between the voltage source and the motor.

14-16 volts DCC is norm for regulated systems and 18 volts is needed for non regulated systems in order to supply the 12 volts to the motor under full load.

The other factor in voltage is speed. More volts translates to more max speed. Frankly most models have a top end speed that greatly exceeds the prototype. This can be especially true in some N scale models. To compensate for this it is common for the modeler to lower the track voltage in both DC and DCC by 2-3 volts.

Hope that helps

Stan Ames

[k9wrangler]

Kato says 12V max right on thier boxes.

Discussions of problems with Kato units on another forum said that Kato was pretty insistant that over voltage was a problem. Sorry do not remember specifics but do remember considerable consternation.

[k9wrangler]

Kato says 12V max right on thier boxes.

Discussions of problems with Kato units on another forum said that Kato was pretty insistant that over voltage was a problem. Sorry do not remember specifics but do remember considerable consternation.

[cacole]

The differences you have noticed between Athearn, Kato, Bachmann, etc. have more to do with the quality of the mechanism than the applied voltage. Some of the better models, such as Kato, Atlas, Spectrum, and Genesis, are geared at a more realistically slow speed than the cheap Athearn, Bachmann, etc. because the cheaper engines are more for the "toy train" market than for modelers. A motor that is rated for 12V DC is not going to be harmed if you run it at a higher voltage, because they do have a "fudge factor" built in to make up for the poorly regulated power packs that come with cheap toy train sets.

[Anonymous]

QUOTE: Originally posted by cacole

Most power packs rated for HO scale actually have an output of 16-18 Volts DC max, even though HO motors are rated for a nominal 12 Volts DC. Power packs put out a higher voltage to make up for poor running qualities of cheaper, older motors used in some models, in an attempt to get them to run more smoothly. If you have newer models, you probably will not run them at full throttle because thay would go unrealistically fast on 16-18 Volts.

That's what I thought too. But then even among modern engines there are differences. For example at 18V Atlas AEM-7 runs like crazy while Spectrum is a lot slower. Kato's are in between.
My only concern is not to burn out the motor, 'cause they ARE marked 12V [X-)]

[cacole]

Most power packs rated for HO scale actually have an output of 16-18 Volts DC max, even though HO motors are rated for a nominal 12 Volts DC. Power packs put out a higher voltage to make up for poor running qualities of cheaper, older motors used in some models, in an attempt to get them to run more smoothly. If you have newer models, you probably will not run them at full throttle because thay would go unrealistically fast on 16-18 Volts.

[darth9x9]

DC - 18V is considered a safe maximum
DCC - 14V is considered a safe maximum

[Fergmiester]

The power packs are designed to compatible with HO engines. (If a guy by the name of Bob B tells you 220V, He's only joking!)

[Anonymous]

I am wondering what is considered maximum safe voltage
for majority HO engines ? Couldn't really find that info anywhere.
Number 12V comes to mind but then a lot of powerpacks are 18V